Commit 83eea879304 for php.net

commit 83eea8793043c47c799193cefe92765a7281dea8
Author: Weilin Du <weilindu@php.net>
Date:   Wed Jul 22 22:35:44 2026 +0800

    [skip ci] Update UPGRADING.INTERNALS for #21607

diff --git a/UPGRADING.INTERNALS b/UPGRADING.INTERNALS
index ef5155e39db..666d7830a5f 100644
--- a/UPGRADING.INTERNALS
+++ b/UPGRADING.INTERNALS
@@ -145,6 +145,9 @@ PHP 8.6 INTERNALS UPGRADE NOTES
     (sendfile, splice, copy_file_range, TransmitFile), and is now used by
     php_stream_copy_to_stream_ex(). The mmap-based copy fallback was removed.
   . Added zend_string_equals_cstr_ci().
+  . Added zend_cstr_append_char(), zend_cstr_concat(), and
+    zend_cstr_concat3() as helper functions to allocate NUL-terminated raw C
+    strings from one or more buffers.
   . Added zend_string_ends_with() and related variants.
   . Added trait support for internal classes.